Socioeconomic disadvantage in childhood is associated with deleterious effects on cognitive development and academic achievement, which in turn have long-lasting ramifications for numerous physical and mental health outcomes across the lifespan. Yet, our understanding of the experiential, physiological, epigenetic and neural pathways through which socioeconomic disparities shape developmental processes is just beginning to emerge. The core contribution of the proposed research would be to further this understanding, by marrying state-of-the-art measurement of brain function, physiology and epigenetics with a sophisticated conceptual and empirical understanding of socioeconomic inequality and experience. In this project, we will investigate how distal factors like SES operate through more proximate factors such as the home language environment and perceived and physiologic stress, and how these proximate factors shape the development of distinct neural and cognitive systems. Two pathways are hypothesized. First, we predict that socioeconomic disparities in the quality and quantity of linguistic stimulation in the home lead to differences in the function of language-specific brain processes, which in turn lead to differences in child language development. Secondly, we predict that SES disparities in perceived stress as well as physiologic stress (cortisol, epigenetics) lead to differences in the function of memory-specific brain processes, which in turn lead to differences in child memory development. To test these hypotheses, a longitudinal study is proposed in which a socioeconomically diverse cohort of 200 children and their families will be followed from birth through age 3. The development of early language and memory skills will be tracked, along with family SES, the home language environment, perceived stress, stress physiology, epigenetics, and brain function. The following specific aims are proposed: (1) Examine longitudinally from birth to 3 the relations among SES, language, memory and brain development. (2) Examine whether socioeconomic disparities in cognitive and brain development are mediated by (a) the home language environment and (b) perceived and physiologic stress. This innovative research will elucidate the pathways linking socioeconomic disparities to specific cognitive and neural outcomes. This is aligned with NICHD?s mission to assist children to ?achieve their full potential for healthy and productive lives.?